Patent GB-468017-A (GB)
Title: Methods and apparatus for hydraulic pressing
IPC: B30B15/16
Filed: 1936-08-13
Abstract: 468,017. Hydraulic presses. BRAUN AKT.-GES., F. Aug. 13, 1936, No. 22343. Convention date, Sept. 16, 1935. [Class 60 (ii)] [Also in Group XXVIII] The control of a hydraulic press for thermoplastic materials is adapted to the working conditions which arise during pressing. The force applied adapts itself automatically to the resistance. The power plunger traverses the greater part of its stroke at invariable high speed. The plunger is returned at high speed and braked at the end of the stroke. The pressure fluid is produced by a revolving- cylinder pump with inclined disc engaged by the piston heads of the kind described in Specification 424,609, [Group XXVIII]. The stroke-adjusting means is subjected to pump pressure which tends to reduce the stroke, and to pressure produced by an auxiliary pump, reservoir, &c., which tends to increase it. The auxiliary pump pressure is greater during the pressing-stroke of the main plunger than during its return. The pressure tending to increase the pump strike is maintained invariable over the initial part of the press-plunger stroke. The auxiliary force at the end of the stroke may increase even with decreasing stroke of the pump. A number of auxiliary forces may be used in step-by-step manner. A spring device may also be used. A stop limits the stroke reduction. The main and auxiliary pumps are enclosed in one housing 1 with a cover 1. The slant disc 3 is adjusted about a shaft 4 until engaged by the stop 83. The pump piston 6 has annular grooves 8, and transverse and longitudinal bores 9, 10. The cylinder boxes are closed by plugs 11. A disc 13 maintains the piston heads in contact with the disc 3. The cylinder block is driven by a shaft 81 through the ring 14. Radial cylinder boxes 15 communicate with suction and discharge connections 17, 19, Fig. 5. The auxiliary pump plungers 21 work in boxes 22 against springs 23 and are reciprocated by a fixed inclined disc 20. The auxiliary cylinder boxes communicate through passages 82 with suction and pressure conduits 24, 25 respectively arranged on opposite sides of the casing, Fig. 6. The inner periphery of the pump housing has grooves 26, 27 and a central part a groove 28 which are supplied from the conduit 25. Further consumers are supplied by way of conduit 33, Fig. 7. The quantity of liquid pumped by the plungers 21 exceeds that required for the passages which effects lubrication. The conduit 33 is connected by way of conduit 43 with the press conduit system. The loading of the valve 85 is effected by a spring and a plunger which is of less area than the valve seat owing to the pressure behind the valve 85. The press plunger 35 has a projection 37 which enters a braking-recess 38. The pump 6 draws in liquid from a reservoir 39 and passes it by passage 19 through the distributing-valve 40 to the cylinder 36. The auxiliary pump draws in liquid by the passage 42 and passes it through conduits 43, 44 to a control valve 45. The disc 3 is adjusted to vary the pressure and quantity of the liquid pumped. The plunger 46 connected to the main pump tends to decrease the stroke. The plungers 48, 88 connected to the auxiliary discharge tends to increase the stroke. The plunger 88 has an adjustable part and a stop so that it is operative only during the latter part of the working stroke of the plunger 35. During the first and greater part of the stroke of the plunger 35, the plunger 48 acts alone to increase the stroke. The chest of the distributing-valve is connected to the cylinder 36 by passages 55, 41 and by conduits 56 .. 59 to the reservoir 39. The valve-chest ends 60, 61 are connected to the casing of a valve 45. The branches 62, 64 have connections with adjustable safety valves 66, 68 connected to the reservoir. The opposed spaces of the control valve are connected by transverse boxes. The valve is angularly adjusted to put the spaces 60, 61 to either the auxiliary pressure conduit 44 or the exhaust. The valve 68 is more heavily loaded than the valve 66 so that the pressure forcing down the plunger 36 is greater than that returning it. Valve 45 is controlled by a clock through a time switch 78, a pinion 79, and a solenoid-operated rack 75.